bug 907960 - backout 905460 r=backout
bug 903480 - [WebGL 2.0] implement TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN - r=jgilbert
Backed out 2 changesets (bug 893184) for Nexus 4 startup crashes.

Backed out changeset e1b2f6bd92c4 (bug 893184)
Backed out changeset 560f18fc3ae3 (bug 893184)